Data centre uninterruptible power supplies including monoblock and modular UPS systems and how to size and install them in a datacentre environment.
A monoblock uninterruptible power supply has a fixed capacity (kVA/kW) and is not scalable except by adding another UPS system of the same capacity to the installation. The two UPS would provide N+1 redundancy or 2X capacity and each UPS would require UPS parallel card and communications cable between these in order to operate in a Master-Slave configuration. The alternative to a monoblock is a modular UPS system that uses UPS modules that slot-into a UPS frame to achieve N+X redundancy or scalable capacity. A modular UPS is therefore easier to scale for future expansion of datacentre loads.
In a datacentre environment, Eco mode can be used to improve the operating efficiency of the uninterruptible power supply. Eco mode can raise the efficiency of the UPS to 99% and is a line interactive type mode of operation only recommended for installations with secure and stable electrical power supplies. Some UPS can be set to operate in an auto-select mode that allows the firmware to make the decision of whether to operate in full on-line or eco mode depending upon the condition of the mains power supply.
If an uninterruptible power supply has a bi-directional rectifier then it may offer the ability to feed power into the mains power supply as part of the National Grid’s Demand Side Response (DSR) program. The site receives a fee for having energy available upon demand and when used. Larger datacentre uninterruptible power supply installations can also support the electricity supply grid frequency by disconnecting and running on battery power. Again this is on demand and can generate revenue for the datacentre operator.